Electric switch



2 Shets-Sheet -l D. W. F ATH ELECTRIC SWITCH May l, 1951 Filed June 24, 1946 &

May l, l 95l D. W. FATH ELECTRIC SWITCH Filed June 24, 1946 2 Sheets-Sheet 2 /l//l//N/l/ patente& May 1, 1951:

ELECTRIC SWITCH Douglas W. Fath, Milwaukee, Wis., assignoto Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application June 24, 1946,'Serial No. 678,'786

3 Claims. (Cl. 200-47) This invention relates to electric switches and is particularly applicable to control switches oi the type commonly known as track type limit switches.

The invention has among its objects to provide an improved track type limit switch which is compact, simple and rugged in Construction, inexpensive and economical to manufacture and positive and reliable in operation when actuated at exceedingly high Operating speeds.

Another object is to providea track type limit switch of the aforesaid character including a cam actuating element which is movable in opposite directions between given circuit controlling positions and which is also capable of emergency overtravel beyond either of said positions.

Another object is to provide a limit switch of the aforesaid type having biasing means associated therewith for eifecting quick movement of the cam actuating element into either of its circuit controlling positions and for also biasing said actuating element against emergency overtravel beyond either of said positions.

various other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification without departing from the spirit and scope of the appended olaims. i

In the drawings,

Figure 1 is an end elevational view of a limit switch embodying the invention with a portion of the enclosing casing thereof broken away and shown in section;

Fig. 2 is a vertical sectional view taken substantially on line 2-2 of Fig. 1;

Figs. 3 and 4 are sectional views taken substantially on lines 3-3 and 4-4, respectively, of Fig. 2, and

Figs. 5 and 6 are schematic views illistrating the switch Operating mechanism in over-travel positions.

Referring to the drawings, the same illustrate a track type limit switch including a plurality of control switches l which are mounted within an enclosing casing 2 and are operable by cams 3 fixed to a square Operating shaft li. Casing 2 is rectangular in shape and is provided with side openings which are closed by a pair of removable cover plates `(i---i and a top opening which is closed by removable cover plate l. The end ,walls 8--8 of casing 2 are provided with openingsvfor receiving end bearings 9 and lo asso- 8 of casing 2.

ciated with shaft 4, and said shaft has a V- shaped Operating lever I I fixed to one end thereof. The bottom wall l2 of casing 2 is provided with mounting feet !3 and the joints between said casing and its associated cover plates 6 and 'l are sealed by gaskets i 4 to provide a waterproof structure.

More specifically, the' limit switch illustrated is provided with three control switches l which are mounted upon an insulating'base !5 (Fig. 3) carried by brackets !6 fixed to the end walls These control switches are of like Construction, each comprising a pair of stationary contacts l'l-l'l carried by binding posts !8 which are mounted upon base [5 and a cooperating bridging contact !9 carried by a lever 20.4 The levers 20 of switches l are arranged in spac ed parallel relation and each is pivotally mounted upon a bracket 22 fixed to base !5 and*` is biased by a spring 23 to maintain its associated bridging contact |9 in circuit closing position. Also each of the l-evers 20 is provided. with an Operating roller 24 which is constructed of insulating material and which rides upon the periphery of its associated cam 3.

The Operating cam 3 are of like Construction, each beingvprovided with a square opening for receiving shaft 4 and being Secured to said shaft by a set screw 25. Also each of the cams 3 is provided with high and low concentric cam faces 26 and 21 and a connecting inclined cam face 28. One of the cams 3, as for example the cam designated by exponent a in Fig. 2 is shown as being mounted upon shaft :i in the full line position illustrated in Fig. 3, and the other cams designated by exponents b and c are shown as being mounted upon said shaft in the position illustrated by dotted lines in Fig. 3. With lever ll positioned as shown in full lines in Fig. 1 the cam surface 27 of cam 3 is positioned for closure of its associated switch l and the cam surfaces 26 of cams 3 and 3 are positioned for opening of their associated switches I. Upon a given degree of counterclockwise rotation of Operating lever li out of the position shown in Fig. 1 cam surface 26 of cam s efects opening of its associated switch and cam surfaces 21 of cams 3 and 3 permit closure of their associated switches l.

Shaft 4 is provided with square end portions which extend beyond bearings 9 and o, and lever li may be Secured to either of said end portions in any one of four different angular positions by means of set screws 3l. As illustrated in Fig, 1 lever [I is mounted upon the left hand 'end portion of shaft 4 in a vertical position and is operable by a pin 32 which travels in a horizontal plane. Shait 4 is provided with a biasing mecham'sm comprising a cam 33 and an associated roller 34 which is carried by a lever 35. Roller 34 is pivotally mounted upon one end of lever 35 and the opposite end of said lever is pivotally supported upon a pin 36 fixed to the right hand end wall 8 of casing 2`, as shown in Fig. 2. Lever 35 is biased by a spring 31 to maintain its associated roller 34 in engagement with the periphery of cam 33. Cam 33 is provided with a square opening for receiving shaft 4 and is secured to said shaft by st screws 38. As shown in Fig. 4, cam 33 is provided with Spaced roller receiving recesses 39 and 40 which are located on opposite sides of a V-shaped cam pro*- jection 4l and between a pair of eccentric cam surfaces 42 and 43.

As is apparent from the foregoing, When lever Il is positioned as shown in full lines in Fig. 1, roller 34 engages within recess 39 in cam 33 to yieldingly hold shaft ai against rotation in op'- posite directions out of the positions shown in Fig. 3. As hereinbefore stated, when lever ii is positioned as shown in Fig. 1 the switch associated With cam s is maintained in closed position and the switches associated with cams a and 3 are maintained in open position. Upon movement of lever ll into the dotted line position shown in Fig. 1, roller 34 engages withinthe recess 40 in cam 33 to yieldingly hold shait 4 against movement in opposite directions out of a position wherein the switch associated with cam 3 is maintained in open position and 'the switches associated with cams 3 and 3 are maintained in closed position.

In connection with the foregoing it will be noted that when lever H is rotated by 'its asscciated Operating pin 32 either in a counterclockwise direction out of the full line position illustrated in Fig. 1 or in a clockwise direction out of the dotted line position illustrated in this figure, roller 34 is moved outwardly against the action of spring 37 by one of the side faces of the cam projection 41 to oppose rotative movement of said lever 'until said roller moves over the peak or high point of said 'cam projection. Roller 34 is then moved inwardly 'under the action of spring 31 across the opposite face of cam projection 4! to move lever H into either its full or dotted line position, as the case may be, with a snap action.

It should also be noted that the above de- ;scribed Operating mechanism is advantageous in `that the same permits safe emergency overtravel -of Operating lever H beyond the positions illustrated in full and dotted lines in Fig. l. Thus assuming that the Operating mechanism is maladjusted so that Operating pin 32 in moving toward the right engages the arm ll of lever Il` to efiect overtravel of said lever beyond the position illustrated in full lines in Fig. 1 into the position illustrated by full lines in Fig. 5. Cam 33 then assumes a position in which the surface 42 thereof is engaged by roller 34 to bias Operating lever ll and shaft 4 for return to the full line position shown in Fig. 1 upon movement of operating pin 32 toward the right beyond arm i l of said Operating lever. On the other hand, assum- 'ing that the Operating mechanism is maladjusted. so that Operating pin 32 in moving toward the left engages arm ll of lever li to effect over- 'travel of said lever beyond the position illus- "trated in dotted lines in Fig. 1 into the position *illustrated by full lines' in 'Fig. G. Cam 33 then assumes a position in which the surface 43 thereof is engaged by roller 34 to bias Operating lever ll and shaft 4 for return to the dotted line p0stion illustrated in Fig. 1 upon movement of operating pin 32 toward the left beyond arm H of said Operating lever. As is apparent from Fig. 3, the cam surfaces 26 and 21 of cams 3 permit a wide degree of overtravel of Operating lever l l and shaft 4 beyond the positions illustrated in full and dotted lines in Fig. 1 without operation of their associated switches l.

As 'shown in Fig. 2, shaft 4 has a lever 45 fixed to the left hand end thereof.. said lever is pro- Vided with projecting arms 46 which cooperate with a fixed stop '41 on the left hand end wall of ca`sir`1g"8 to permit a limited degree of overtravel of :shaft 4 and its associated Operating lever l l in opposite directions beyond the positions illustrated by full and dotted lines in Fig. 1. What I claim as new and desire to secure by Letters Patent is:

1. In combi-nation, a control switch having a rotatable cam Operating eiement movable in opposite directions between two normal limits for opening and closure of the *switch and being capable of 'emergency over'travel a given degree beyond either of its normal limits without effecting change in the position of ;the-switcl1,-n1eans limiting said cam Operating element to overtravel to said given'degree beyond 'either of its normal limits, an Operating lever *fixed to said cam operating -element, a traveling 'Operating part for said lever, said Operating part 'being normally associated with said 'lever to effect movement of said cam -operating element in opposite directions between its normal limits and being operative upon maiadjustment with respect to said lever to cause overtravel of 'sa-id cam Operating element beyond its'normal limits, and a cam biasing mechanism associated 'with said cam Operating element for'efiecting 'snap movement -of :sa-id cam Operating element into eitheref its normal' iimits upon a given --movement thereei away `'from the other of its `'normal limits and for also eh ecting return of saidcam element 'to either of "its normal limits -upon-overtravel therebeyond.

'2. A limitswitchnreeh'an-ism comprising anenclosing casing, an insulatin'g base mountedwithin said `casing, a -pluraiity of control switches mounted upon *said insulating base 'and each biased toward circuit closin'g--position, a cam operating element for said switches rota-tably mounted within said -casing, said cam Operating element being movable in 'opposite directions between 'two limits to eiiect` opening and closure -of said switches selectively and being -capable of emergency overtravel 'a given 'degree beyond either` of its normal limits without effecting change *in the 'position of said switches, means l-imitingsaid `cam operatingele'nent to overtravel to said given degree beyond either of its normal limits, an operating lever fixed to said'cam operating element, a' traveling Operating 'part-associated with said lever, said Operating part 'being normally associated with -said lever to eect -movement of said cam operatingelement in opposite directions "between -its normal limits *and being Operative upon maladjustment -wi-th re- *spect to said lever to cause overtravel of-said cam Operating element 'beyond its 'normal limits, 'and a cam biasing mechan'ism associated with *saidcam Operating element for effecting snap movement of said cam 'ojperating element into 'either 'of its norml limits `upon a given movemerit thereof away i-rom the dther o'f its normal limits and for also efiecting return of said cam Operating element to either of its normal limits upon overtravel therebeyond.

3. In combination, a control switch having a rotatable cam Operating element movable in opposite directions between two normal limits for opening and closu'e of the switch and being capable of emergency overtravel a given degree beyond either of said limits without change in the position of said switch, means limiting said cam Operating element to overtravel to said given degree beyond either of its normal limits, a V- shaped Operating lever fixed to said cam operating element, a traveling Operating part for said lever, said Operating part being normally operable by engagement with the opposing sides of the arms of said lever to effect movement of said cam element in opposite directions between its normal limits, and said Operating part upon maladjustment of said lever With respect thereto being operabie by engagement with the outer sides of the arms of said lever to effect overtravel of said cam Operating element beyond its normal limits, and a cam biasing mechanism associated with said cam Operating element for efiecting snap movement of said cam Operating element into either of its normal limits upon a given movement thereof away from the other of its normal limits, and for also effecting return of said cam element to either of its normal limits upon overtravel therebeyond.

DOUGLAS W. FATH.

REFERENCES CITED The following reierences are of record in the file of this patent:

UNITED STATES PATENTS France Feb. 15, 1932 

